KR20080100986A - Manufacturing method for producing tin oxide powder, reaction apparatus for producing the same, and tin oxide powder manufactured by the same - Google Patents

Abstract

A reactor for manufacturing tin oxide powders is provided to raise a reaction speed of a nitric acid and a metal tin by setting up an ultrasonic wave generating unit supplying the ultrasonic wave. A manufacturing method of the tin oxide powder is provided to manufacture minute tin oxide powders and to increase the reactor reaction speed by supplying the ultrasonic wave within the reactor, infusing a gas and adding a step for bubbling. A reactor for manufacturing tin oxide powders(400) comprises a reactor(420), a support unit(440) for supporting a metal tin and an ultrasonic wave generation unit(480). The support unit(440) for supporting a metal tin is arranged and separated a bottom from the reactor. The ultrasonic wave generation unit supplies an ultrasonic wave to the reactor. The metal tin is reacted with an aqueous nitric acid solution and a precipitate is generated. The reactor for manufacturing tin oxide powders additionally includes an aerator for supplying a gas and generates bubbles.

Description

Manufacturing method for producing tin oxide powder, reaction apparatus for manufacturing the same, and tin oxide powder produced therefrom {Manufacturing method for producing tin oxide powder, reaction apparatus for producing the same, and tin oxide powder manufactured by the same}

1 is a perspective view showing a reaction apparatus for producing tin oxide according to an embodiment of the present invention.

Figure 2 is a perspective view showing a reaction apparatus for producing tin oxide according to another embodiment of the present invention.

3 is a perspective view showing a reaction apparatus for preparing tin oxide according to another embodiment of the present invention.

Figure 4 is a perspective view showing a reaction apparatus for producing tin oxide according to another embodiment of the present invention.

5 is a conceptual diagram illustrating a reaction apparatus for preparing tin oxide according to another embodiment of the present invention.

6 is a flowchart illustrating a process of preparing tin oxide powder according to an embodiment of the present invention.

7 is a graph showing the results of the X-ray diffraction pattern of the tin oxide powder prepared by Comparative Example 1 of the present invention.

8 is an electron scanning micrograph of the surface of a sintered body made of tin oxide powder prepared according to Example 3 of the present invention.

9 is an electron scanning micrograph of the surface of a sintered body made of tin oxide powder prepared according to Example 4 of the present invention.

10 is an electron scanning micrograph of the surface of a sintered body made of tin oxide powder prepared according to Example 5 of the present invention.

[Description of Major Symbols in Drawing]

50: metal tin

100, 200, 300, 400, 500: reactor for the production of tin oxide

120, 220, 320, 420, 520: reactor

140, 240, 340, 440: base unit for supporting metal tin

160: magnetic rod

180, 280, 380, 480, 580: Ultrasonic Generating Unit

182, 282, 382, 482, 582: oscillators

184, 284, 384, 484, 584: oscillator

270, 370, 470: aeration device

272, 372, 472: gas supply (same as 510)

274, 374, 474: gas delivery unit

276, 376, 476: bubble generator

490: medium

510: Mass Flow Controller (MFC)

540: condenser

560: valve

590: Gas Chromatography (GC) with Thermal Conductivity Detector (TCD)

The present invention relates to a method for producing a tin oxide powder, a reaction apparatus for producing the same, and a tin oxide powder prepared therefrom, and more particularly, high density required for vacuum deposition of high quality transparent electrode layers of display devices such as LCDs, ELs, and FED devices. The present invention relates to a method for producing tin oxide powder that can be used for the production and charging of indium tin oxide (ITO) targets, and electrostatic prevention, a reaction apparatus for producing the same, and tin oxide powder prepared therefrom.

ITO film, which is widely used as a transparent electrode, is generally formed by sputtering an ITO target and coating it on an insulating substrate such as a glass substrate. The ITO target used here is formed by sintering at high temperature by forming ITO powder into a constant shape. Get by In general, in order to coat a high quality ITO film on a substrate by the sputtering method, the sintered density of the ITO target must be high. This means that when a low density ITO target is used, nodules are easily formed on the surface of the ITO film. This is because the quality and the process yield are lowered. Therefore, in order to form a high quality ITO transparent electrode layer, a high density ITO target should be used, and in order to manufacture such a high density ITO target, the average particle size is small, the specific surface area is large, and the particle size distribution is uniform, so that indium oxide and solid solution (solid) It requires a fine tin oxide powder that can achieve a good solution). It is also known that the more uniform the crystal size of the tin oxide powder is in each direction, the easier it is to form a solid solution.

Conventional techniques for synthesizing tin oxide powders include a method using a compacting method in which a tin oxide precursor solution or a precursor solution thereof is neutralized and extruded at high temperature and high pressure. However, the tin oxide produced by this method has the possibility of further contamination because it uses tin salt as a precursor. To prevent this, the consumption of tin salt, which is a reactant, is high, and the process must be performed at high temperature and high pressure. There is a weak point.

In addition, there is a method of obtaining tin oxide powder by electrooxidizing tin in an aqueous solution using tin metal as an anode and ammonium nitrate solution as an electrolyte to obtain metastannic acid, followed by filtration, washing, and sintering. However, the above method has a disadvantage in that it is difficult to apply to mass production because of slow reaction rate, high energy consumption, and problems in working safety.

In addition, the gas phase method, which is well known as a method capable of synthesizing nano-sized powder, is difficult to be applied to mass production, and thus it is limited to only a small amount of synthesis of a special powder.

The method generally used as a synthesis method of tin oxide powder for producing an ITO target is the liquid phase method. In order to easily control the impurity content, a high purity metal tin is used as a reactant, and tin oxide powder is prepared by reacting the metal tin with an acid solution. However, since the reaction rate is slow, in order to keep the temperature of the reaction system high or to speed up the oxidation reaction rate of the metal surface, a method of reducing the size of metal tin, which is a reactant, is used. However, all of the above methods are difficult in producing high quality tin oxide powder in actual process because of the additional energy consumption, complicated operation and dangerous operation to produce fine tin oxide powder, and difficult to check the progress of the reaction. .

In view of the above problems, the present invention provides a reaction apparatus for preparing tin oxide powder that can be used to manufacture a high density ITO target by improving the structure of the reaction apparatus for preparing tin oxide.

The present invention also provides a method for producing a tin oxide powder having a higher crystallization rate and increasing the reaction rate of metal tin and nitric acid using the reaction apparatus for tin oxide production.

It is another object of the present invention to provide a tin oxide powder which can grow uniformly in each crystal direction to produce a high density target.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

The reaction apparatus for manufacturing tin oxide according to an aspect of the present invention includes a reactor, a support unit for supporting metal tins spaced a predetermined distance from the bottom surface of the reactor, and an ultrasonic wave generating unit for supplying ultrasonic waves into the reactor. A reaction apparatus for producing a precipitate by reacting tin with an aqueous solution of nitric acid.

In addition, the reaction apparatus for producing tin oxide may further include an aeration device for generating bubbles by supplying gas. The aeration device includes a gas supply unit for supplying gas, a gas transfer unit for transferring the gas supplied from the gas supply unit into the reactor, and a bubble generating unit for blowing a gas transferred from the gas transfer unit into the reactor to generate bubbles do.

The gas is characterized in that at least one gas selected from the group consisting of inert gas, nitrogen gas and compressed air.

In addition, the reaction apparatus for preparing tin oxide may further include gas chromatography (GC) equipped with a thermal conductivity detector (TCD).

The ultrasonic wave generation unit included in the reaction apparatus for producing tin oxide includes an oscillator and a vibrator. The oscillator is disposed outside the reactor and generates ultrasonic waves, and the vibrator is disposed inside the reactor or attached to an outer wall of the reactor, and serves to deliver ultrasonic waves generated from the oscillator into the reactor.

Alternatively, the ultrasonic wave generating unit may include an oscillator for generating ultrasonic waves and a vibrator for transmitting the ultrasonic waves to the reactor, and may supply ultrasonic waves to the reactor through a medium disposed between the reactor and the ultrasonic wave generating unit.

The intensity of the ultrasonic wave is characterized in that 0.1 to 3kW.

Method for producing a tin oxide powder according to an aspect of the present invention includes a precipitation forming reaction step of forming a precipitate by introducing metal tin, water and nitric acid in the reactor, wherein the precipitation forming reaction step while supplying ultrasonic waves into the reactor , Blowing a gas to bubble the inside of the reactor.

The precipitation forming reaction step includes introducing metal tin and water into the reactor, blowing gas into the reactor, feeding ultrasonic waves into the reactor, and adding nitric acid into the reactor.

The ultrasonic waves are supplied into the reactor from before the nitric acid is added until the end of the precipitation formation reaction, and the intensity of the ultrasonic waves is 0.1 to 3 kW.

The gas is at least one gas selected from the group consisting of inert gas, nitrogen gas and compressed air, characterized in that the inside of the reactor is supplied at a rate of 1 to 5 times the reactor capacity per minute.

The bubbling may be maintained such that the entire surface of the metal tin is exposed to the nitric acid during the precipitation formation reaction and may also cause the bubbling to occur on the surface of the metal tin.

The precipitate formed from the precipitation formation reaction step is aged for 11 to 13 hours and neutralized to pH 4 to 8.

The tin oxide powder according to one feature of the present invention has a crystal size in the [101] direction with respect to a crystal size in the [110] direction of 0.4 to 1.6 times, and a crystal size in the [211] direction of 0.6 to 1.4 times.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view showing a reaction apparatus for producing tin oxide according to an embodiment of the present invention.

Referring to FIG. 1, the reaction apparatus 100 for manufacturing tin oxide includes a reactor 120, a magnet rod 160, a support unit 140 for supporting metal tin, and an ultrasonic wave generating unit 180.

In preparing the tin oxide powder, first, the metal tin 50 is placed in the reactor 120, and water and nitric acid are introduced into the reactor 120. At this time, the magnetic rod 160 is rotated using a magnetic stirrer and stirred. The reaction of metal tin with nitric acid produces a precipitate of metastannic acid (H ₂ SnO ₃ ). Scheme 1 below shows the surface oxidation of metal tin when metal tin is present in the nitric acid solution.

Sn + ₂ HNO ₃ → H ₂ SnO ₃ + NO + NO ₂

Since the reaction of metal tin and nitric acid starts to occur on the surface of the metal tin, which is the contact surface, metastanic acid is formed on the surface of the metal tin, and bubbles of NOx gas (NO and NO ₂ gas) also occur on the surface of the metal tin. Therefore, the bubbles of the metastanic acid and the NOx gas, which are products, remain on the surface of the metal tin, thereby substantially reducing the reaction area of the metal tin and nitric acid, thereby lowering the reaction rate.

In addition, the conventional reaction apparatus does not include the support unit 140 for supporting the metal tin, and the metal tin reacts with the nitric acid aqueous solution in contact with the bottom surface of the reactor. As a result, the contact area of the surface where the metal tin and nitric acid can react is substantially reduced, and as the reaction proceeds, the metal tin is covered with the metasteronic acid, thereby limiting the speed of the reaction.

Accordingly, in one embodiment of the present invention, by including the support unit 140 for supporting the tin tin in the reaction apparatus for producing tin oxide, metastainonic acid is precipitated at the bottom of the reactor 120 to react the metal tin (50) ) And at the same time reduce the area where the metal tin 50 contacts the bottom surface of the reactor 120, thereby increasing the contact area with nitric acid.

The support base unit 140 for supporting the metal tin is spaced apart from the bottom of the reactor 120 by a predetermined distance, and the shape of the support unit 140 may have various shapes in addition to the ladder shown in FIG. 1. The location of the connection portion of the support unit 140 and the reactor 120 may also vary from the bottom surface of the reactor shown in FIG. 1, the side surface of the reactor, the top of the reactor, or a combination thereof.

As shown in FIG. 1, the metal tin is positioned on the metal tin support base 140 so that only the bottom surface of the metal tin is in contact with the metal tin support pedestal 140. According to various positions and shapes of the 140, the side surface or the top surface other than the bottom surface of the metal tin or a combination thereof may be in contact with the pedestal 140.

The shape of the part contacting the metal tin 50 in the support unit 140 for the metal tin support may have various shapes such as an edge having an edge and an open center, a mesh shape, and a ladder shape. Thus, unlike the prior art in which the bottom surface of the metal tin is in complete contact with the bottom surface of the reactor 120 and thus the reaction with nitric acid does not occur smoothly, some or all of the bottom surface of the metal tin may be in contact with the nitric acid. The reaction area can be increased.

The material of the support unit 140 for supporting the metal tin is made of quartz, and in addition to quartz, any material capable of withstanding high nitric acid and high temperature may be used.

In addition, the ultrasonic generating unit 180 located outside the reactor 120 includes an oscillator 182 and a vibrator 184. The oscillator 182 generates ultrasonic waves by external power supply, and the vibrator 184 serves to transmit the ultrasonic waves by vibration. In the present embodiment, the vibrator 184 is attached to the outside of the reactor 120, the present invention is not limited to this, the vibrator 184 may be located inside the reactor 120. In addition, the position at which the vibrator 184 is attached to the reactor 120 may vary, and the number of the vibrators 184 attached may also be one or more.

By installing the ultrasonic wave generation unit 180 in the reaction apparatus 100 for manufacturing tin oxide, hot spots are generated in the reaction solution by supplying high energy with ultrasonic waves, which causes bubbles of micro size locally. As it explodes, it is easy to remove the metastanic acid produced on the surface of the metal tin 50. In addition, the generated metastatic acid may be prevented from agglomerating with each other as they accumulate on the bottom of the reactor 120, thereby improving physical properties of the manufactured tin oxide powder.

Hereinafter, the case where the reaction apparatus for tin oxide production further includes an aeration apparatus capable of bubbling gas will be described.

Figure 2 is a perspective view showing a reaction apparatus for producing tin oxide according to another embodiment of the present invention.

Referring to FIG. 2, the reaction apparatus 200 for manufacturing tin oxide includes a reactor 220, a support unit 240 for supporting metal tin, an aeration device 270, and an ultrasonic wave generation unit 280. Since the reactor 220, the metal tin support base unit 240, and the ultrasonic wave generation unit 280 are the same as those described with reference to FIG. 1, overlapping descriptions thereof will be omitted. Hereinafter, the aeration device 270 will be described in detail. Let's explain.

The aeration device 270 includes a gas supply unit 272, a gas transfer unit 274, and a bubble generator 276. The gas supply unit 272 serves to supply a predetermined amount of gas into the reactor 220 over time, and the gas transfer unit 274 transfers the gas from the gas supply unit 272 to the inside of the reactor 220. The gas is characterized in that at least one gas selected from the group consisting of inert gas, nitrogen gas and compressed air. Helium (He) or argon (Ar) gas may be used as the inert gas, but the present invention is not limited thereto.

 The gas transferred by the gas transfer unit 274 is bubbled inside the reactor 220 through the bubble generator 276. According to the above Reaction Scheme 1, when the NO x gas generated by the reaction between the metal tin and nitric acid is removed, the reaction of metastainic acid formation in chemical equilibrium theory is promoted. Therefore, when ultrasonic waves are supplied while bubbling gas into the reactor, high energy is supplied to the NOx gas clinging to the surface of the metal tin 50 in the form of bubbles and the NOx gas dissolved in the reaction solution to burst by sudden expansion. By removing these smoothly, the reaction rate of metal tin and nitric acid can be increased. In addition, by supplying ultrasonic energy while bubbling gas, not only large bubbles but also micro bubbles are generated more easily, thereby causing the product material that is stuck to the surface of the metal tin 50 to be released from the surface of the metal tin 50, thereby causing the metal tin. (50) and nitric acid can be made smooth.

When blowing the gas while supplying ultrasonic waves into the reactor, the gas may be supplied at a constant speed using a device such as a mass flow controller (MFC). At this time, the velocity of blowing gas and the intensity of the ultrasonic wave are determined in consideration of the capacity of the reactor, the weight of metal tin, and the concentration and volume of nitric acid added.

If the gas feed rate is too slow, it may be difficult to separate bubbles or product material that cling to the surface of the metal tin, on the contrary, if the gas feed rate is too fast, there may be problems in working stability and economics. Therefore, in the present invention, gas is supplied at a rate of 1 to 5 times the reactor capacity per minute. Preferably gas is supplied at a rate of 2 to 3.5 times the reactor capacity per minute, more preferably gas is supplied at a rate of 2 to 3 times the reactor capacity per minute. In addition, excessive supply of ultrasonic waves affects the life of the reaction system, and if it is too small, it may accelerate the aggregation of the generated metastanic acids. Therefore, the intensity of the ultrasonic wave is supplied in the range of 100W to 3kW.

Hereinafter, another Example which mounts an ultrasonic wave generation unit in the said reaction apparatus for tin oxide manufacture is demonstrated.

3 is a perspective view showing a reaction apparatus for preparing tin oxide according to another embodiment of the present invention.

Referring to FIG. 3, the reaction device 300 for manufacturing tin oxide includes a reactor 320, a support unit 340 for supporting metal tin, an aeration device 370, and an ultrasonic wave generation unit 380.

The ultrasonic wave generating unit 380 includes an oscillator 382 and a vibrator 384, and the vibrator 384 is positioned at an outer side of the reactor 320 to supply ultrasonic waves into the reactor 320. In the present embodiment, two vibrators 384 are attached to the outer side of the reactor 320, but the present invention is not limited thereto, and the number and location of the vibrators 384 may vary depending on the case.

Figure 4 is a perspective view showing a reaction apparatus for producing tin oxide according to another embodiment of the present invention.

Referring to FIG. 4, the reaction apparatus 400 for manufacturing tin oxide includes a reactor 420, a support unit 440 for supporting metal tin, an aeration device 470, and an ultrasonic wave generating unit 480. 480 includes an oscillator 482 and an oscillator 484.

The ultrasonic wave generating unit 480 is disposed to surround the reactor 420 from the outside, and the reactor 420 through a medium 490 disposed between the reactor 420 and the ultrasonic wave generating unit 480. ) To supply ultrasonic waves. The medium 490 may generally use water, but is not limited thereto. The position or number of oscillators 482 and vibrators 484 existing in the ultrasonic wave generation unit 480 may be arbitrarily changed as necessary.

Hereinafter, a case in which the reaction apparatus for preparing tin oxide further includes a measuring device capable of confirming the reaction rate in real time will be described.

5 is a conceptual diagram illustrating a reaction apparatus for preparing tin oxide according to another embodiment of the present invention.

Referring to FIG. 5, the reaction apparatus 500 for manufacturing tin oxide further includes gas chromatography (Gas Chromatography, GC) 590 equipped with a thermal conductivity detector (TCD). The reaction apparatus 500 for producing tin oxide is a gas chromatograph equipped with a gas flow control device 510, a reactor 520, a condenser 540, a valve 560, an ultrasonic wave generating unit 580, and a thermal conductivity detector. Graphics 590 may be included and may include only some of the configurations as needed.

The reaction apparatus 500 for manufacturing tin oxide may include a support unit for supporting metal tin in the reactor 520. It also includes a case in which the aeration device is included in the reaction device to bubble the gas.

Hereinafter, a case in which the reaction apparatus for preparing tin oxide further includes gas chromatography equipped with an aeration apparatus, an ultrasonic wave generator, and a thermal conductivity detector will be described.

When the gas is supplied from the aeration device, the gas is blown into the reactor 520 in the I ₁ direction at a constant speed by using the gas flow precision control device 510. The constant gas supply method includes a quantitative supply using a gas flow precision control device (MFC) and a constant pressure supply using a gas pressure regulator, and the constant pressure supply is used when the pressure inside the reactor changes. Since it is not constant, in this invention, a gas flow precision control apparatus (MFC) is used. The I ₁ direction is not limited to blowing gas through the upper portion of the reactor 520 as shown in FIG. 3, and includes all cases of supplying gas into the reactor 520.

NOx gas produced by the reaction of metal tin and nitric acid in the reactor 520 and the gas supplied from the aeration device pass through the condenser 540 and then discharged in the I ₂ direction, some of which may cause the valve 560 to The concentration of the NOx gas is measured in gas chromatography 590 equipped with a thermal conductivity detector, which is sampled through. As the valve 560, a 6-way valve that operates automatically with compressed air may be used, but the present invention is not limited thereto. By measuring the concentration of NOx gas generated by the reaction of the metal tin and nitric acid, the reaction rate of the metal tin and nitric acid can be known, and the end point of the reaction can be found, thereby increasing the efficiency of the manufacturing process.

Hereinafter, a method for producing tin oxide powder according to the present invention will be described.

6 is a flowchart illustrating a process of preparing tin oxide powder according to an embodiment of the present invention.

When metal tin, water, and nitric acid are added to the reactor (S11), metal tin is dissolved (S12) by nitric acid, and metastatic acid is formed as a precipitate (S13), as shown in Scheme 1 above. After recovering the resulting precipitate and adding water, the pH is adjusted for a predetermined time to undergo a aging process (S14) and neutralize. Thereafter, the slurry obtained by the above method is washed (S15), filtered, dried (S16) and pulverized, and then calcined (S17) at a predetermined temperature to obtain tin oxide powder (S18).

The present invention may include a step of bubbling the inside of the reactor by irradiating ultrasonic waves and blowing gas into the reactor in the precipitation forming step (S11 to S13) by the reaction of the metal tin and nitric acid. The precipitation forming reaction step (S11 to S13), the step of introducing metal tin and water in the reactor, blowing a gas into the reactor, supplying ultrasonic waves into the reactor and adding nitric acid in the reactor Steps.

The ultrasonic waves are supplied inside the reactor from before the addition of nitric acid to the end of the precipitation forming reaction. Therefore, when the precipitation formation reaction by nitric acid input is continued for 12 hours, the ultrasonic supply is also continued for 12 hours.

The gas is characterized in that at least one gas selected from the group consisting of inert gas, nitrogen gas and compressed air. Helium (He) or argon (Ar) may be used as the inert gas, but the present invention is not limited thereto.

In one embodiment of the present invention, the method for producing a tin oxide powder is bubbling with gas while irradiating the inside of the reactor with ultrasonic waves to maintain the entire surface of the metal tin during the precipitation forming reaction (S13) to be exposed to the nitric acid Characterized in that it comprises a. The reaction between metal tin and nitric acid causes bubbles of the material and NOx gas to adhere to the surface of the metal tin, so that the inside of the reactor is bubbled with ultrasonic waves and gas to bubble bubbles between the product material and the NOx gas. Departure from the surface allows the entire surface of the metal tin to be exposed to nitric acid. This action can be accelerated by the additional supply of ultrasonic energy and can reduce the bubbling rate, which indicates maximum efficiency. This is an advantage in terms of convenience, safety and economy of work. In addition, when the bubbling occurs on the surface of the metal tin, bubbles of the product and NOx gas that cling to the surface of the metal tin may be more effectively removed. In addition, by bubbling gas into the reactor, the reaction temperature of the metal tin and nitric acid can be substantially lowered, thereby lowering the manufacturing cost.

Hereinafter, with regard to the method for producing the tin oxide powder of the present invention, the time for ripening the precipitate and the pH for neutralizing the precipitate will be described.

In the present invention, in the preparation of tin oxide, the precipitation produced by reacting the metal tin with an aqueous solution of nitric acid is adjusted to pH 4 to 8 and subjected to a step of ripening for 11 to 13 hours (S14). The aging process (S14) may be applied regardless of whether or not bubbling in the precipitation production reaction process. That is, the aging process may be applied not only when bubbling is applied to generate precipitation but also when not bubbling.

The metastanic acid precipitate produced by the reaction of metal tin and nitric acid is recovered after the reaction is completed and aged for a predetermined time at a controlled pH. At this time, the uniformity of the primary particle size, specific surface area and crystal growth direction of the prepared tin oxide powder varies depending on the aging time and pH. If the aging time is short, the concentration of ions remaining in the precipitate is high, the primary particle size of the tin oxide powder is large, the specific surface area is small, and the crystal growth direction is nonuniform. On the contrary, too long aging time reduces the efficiency of the manufacturing process and increases the particle size of the tin oxide powder. In addition, without proper aging time, the crystal growth direction becomes nonuniform, which causes the sintered density to be lowered in the production of the ITO target. Therefore, in the present invention, the aging time of precipitation is 11 to 13 hours, preferably about 12 hours.

Ammonia water was added to the metastatic acid precipitate to adjust the pH to mature, and then neutralized. Next, pure water was added by performing the washing of metastatic acid through a centrifuge (S15), and then using a paper filter. Filter and dry (S16).

Aggregation occurs by physical bonding between particles during the aging process (S14) after precipitation, which is then changed to chemical bonding in the calcination process (S17). In order to prevent this, there is a method of adding an external additive, but the impurity content may be increased, and the reaction solution is not suitable because of the concentrated nitric acid solution. Therefore, the present invention neutralizes precipitation in the range of pH 4 to 8 during the aging process, using the fact that the charge on the surface of the particles changes with pH rather than external additives.

Hereinafter, the method of preparing the tin oxide powder according to the present invention will be described in more detail with reference to the following Examples, which are illustrative examples for explaining the production method according to the present invention in more detail. It is not limited to an Example.

Example 1

A reactor for producing tin oxide was used, which consisted of a reactor, a support unit for supporting metal tin, and an ultrasonic wave generating unit for supplying ultrasonic waves into the reactor through a medium. As the ultrasonic wave generating unit, a DH · D300H model manufactured by Korean Science was used.

After the metal tin was placed on the support unit for supporting the metal tin in a reactor having a capacity of 2 L, distilled water corresponding to 2.5 times the mass of the metal tin was added thereto, and 60% nitric acid at a room temperature was added with the same weight as the distilled water. The magnetic rod was rotated with a magnetic stirrer and stirred, and an ultrasonic wave was supplied using an ultrasonic generating unit, and reacted for 12 hours from the start of nitric acid addition to form a precipitate. Then, the metal tin remaining without reacting with nitric acid was washed and dried to measure mass.

Precipitated metastannic acid (metastannic acid) was added to 1.25kg of water, aged for 24 hours and neutralized with 28% ammonia water. The slurry thus obtained was washed three times using a centrifuge, and then 100 mL of distilled water was further added and filtered using a paper filter. The metastanic acid obtained after the filtration was dried in a 105 ° C. drying oven for 24 hours, and then ground for 1 minute using a grinder, and calcined at 600 ° C. for 3 hours to obtain a tin oxide powder. The mass of the metal tin remaining after the reaction is summarized in Table 1, and the primary particle size and specific surface area of the resulting tin oxide powder are summarized in Table 2.

Example 2

The reaction apparatus 400 for preparing tin oxide shown in FIG. 4 was used. After putting the metal tin 50 on the support base unit 440 for supporting the metal tin in the reactor 420 having a capacity of 2L, distilled water corresponding to 2.5 times the mass of the metal tin was added thereto, and 60% nitric acid at 60 ° C. Was put in the same weight as. At this time, nitrogen gas was blown into the reactor at a rate of 10 L per minute using the aeration device 470, and ultrasonic waves were supplied before the addition of nitric acid and then supplied for 12 hours until the end of the reaction. After 12 hours from the start of nitric acid addition, the metal tin remaining without reacting with nitric acid was washed and dried to measure mass.

Precipitated metastatic acid was added to 1.25 kg of water and aged for 24 hours to neutralize with 28% ammonia water. The slurry thus obtained was washed three times using a centrifuge, and then 100 mL of distilled water was further added and filtered using a paper filter. The metastanic acid obtained after the filtration was dried in a 105 ° C. drying oven for 24 hours, and then ground for 1 minute using a grinder, and calcined at 600 ° C. for 3 hours to obtain a tin oxide powder. The mass of the metal tin remaining after the reaction is summarized in Table 1, and the primary particle size and specific surface area of the resulting tin oxide powder are summarized in Table 2.

Example 3

The reaction apparatus 400 for preparing tin oxide shown in FIG. 4 was used. After putting the metal tin 50 on the support base unit 440 for supporting the metal tin in the reactor 420 having a capacity of 2L, distilled water corresponding to 2.5 times the mass of the metal tin was added thereto, and 60% nitric acid at 60 ° C. Was put in the same weight as. At this time, nitrogen gas was blown into the reactor at a rate of 1 L per minute using the aeration device 470, and ultrasonic waves were supplied before the addition of nitric acid and then supplied for 12 hours until the end of the reaction.

Precipitated metastatic acid was added to 1.25kg of water and aged for 9 hours to neutralize with 28% ammonia water. The slurry thus obtained was washed three times using a centrifuge, and then 100 mL of distilled water was further added and filtered using a paper filter. The metastanic acid obtained after the filtration was dried for 24 hours in a 105 ° C. drying oven, pulverized for 1 minute using a grinder, and calcined at 600 ° C. for 3 hours to obtain a tin oxide powder.

The tin oxide powder thus obtained was used to prepare an ITO target, and the relative sintered densities were measured. The results are summarized in Table 3 in comparison with the relative sintered densities of the ITO targets prepared in Examples 4 and 5. In addition, the surface of the ITO target was photographed with an electron scanning microscope and shown in FIG. 8.

Example 4

A tin oxide powder was prepared in the same manner as in Example 3 except that the precipitated metastatic acid was aged for 12 hours.

The tin oxide powder thus obtained was used to prepare an ITO target, and the relative sintered density was measured to determine the relative sintered density and the difference between the sintered bodies prepared in Example 3, and the results are summarized in Table 3. In addition, the surface of the ITO target was photographed with an electron scanning microscope and shown in FIG. 9.

Example 5

A tin oxide powder was prepared in the same manner as in Example 3 except that the precipitated metastatic acid was aged for 15 hours.

The tin oxide powder thus obtained was used to prepare an ITO target, and the relative sintered density was measured to determine the relative sintered density and the difference between the sintered bodies prepared in Example 3, and the results are summarized in Table 3. In addition, the surface of the ITO target was photographed with an electron scanning microscope and shown in FIG. 10.

Comparative Example 1

A reaction apparatus for producing tin oxide was used, which consisted of a reactor and a support unit for supporting metal tin.

The metal tin was placed on the support base for supporting the metal tin in a reactor having a capacity of 2 L, and then distilled water corresponding to 2.5 times the mass of the metal tin was stirred with a magnetic stirrer. Input. Reaction was formed for 12 hours from the start of nitric acid addition to form a precipitate. Then, the metal tin remaining without reacting with nitric acid was washed and dried to measure mass.

Precipitated metastannic acid (metastannic acid) was added to 1.25kg of water, aged for 24 hours and neutralized with 28% ammonia water. The slurry thus obtained was washed three times using a centrifuge, and then 100 mL of distilled water was further added and filtered using a paper filter. The metastanic acid obtained after the filtration was dried in a 105 ° C. drying oven for 24 hours, and then ground for 1 minute using a grinder, and calcined at 600 ° C. for 3 hours to obtain a tin oxide powder. The mass of the metal tin remaining after the reaction is summarized in Table 1, and the primary particle size and specific surface area of the resulting tin oxide powder are summarized in Table 2.

Weight before start of reaction (A) Weight after completion of reaction (B) A-B Reaction Rate (A-B) / A Example 1 251.32 g 82.40 g 168.92 g 0.67 Example 2 257.80 g 0g 257.80 g 1.00 Comparative Example 1 271.15 g 119.27 g 151.88 g 0.56

dXRD (nm) Specific surface area (m ² / g) Example 1 31.7 12.43 Example 2 17.7 14.78 Comparative Example 1 23.1 10.08

dXRD (nm) Relative Sintered Density Difference (g / cm ³ ) Specific surface area (m ² / g) 1st 2nd 3rd Example 3 12 15 72 0 11.48 Example 4 29 13 24 0.0056 11.46 Example 5 17 27 23 0.0047 10.99

As a result of Table 1, the case of Examples 1 and 2 including the support unit and the ultrasonic wave generating unit for metal tin support in the reaction apparatus for producing tin oxide of Comparative Example 1 not including the support unit and the ultrasonic wave generating unit It can be seen that the reaction rate of metal tin and nitric acid was higher than that. In addition, it can be seen that the case of Example 2 in which gas was blown into the reactor by the aeration device showed the highest reaction rate. That is, under the same conditions, the reaction apparatus for preparing tin oxide includes a support unit for supporting tin and an ultrasonic wave generating unit, and shows that the reaction rate of metal tin and nitric acid is highest when the gas is bubbled through the aeration apparatus.

In Table 2, dXRD is a value calculated using Sherr's equation from the half width (FWHM) obtained from the X-ray diffraction pattern of the tin oxide powders prepared according to Examples 1 to 2 and Comparative Example 1, from which the primary particle size It can be seen. 7 is a graph showing the X-ray diffraction pattern results of the tin oxide powder prepared by Comparative Example 1, in which the horizontal axis represents the diffraction angle (2 theta) and the vertical axis represents the diffraction intensity (intensity). The dXRD values in Table 2 were obtained from the X-ray diffraction patterns of the tin oxide powders prepared in Example 1, Example 2 and Comparative Example 1, respectively, and then the first (1st) peak and second (2nd) in the diffraction pattern. ) Is the average of the values calculated from the half widths of the peak and the third (3rd) peak. From the results in Table 2, it can be seen that in Example 2, the primary particle size is the smallest.

In Table 2, the specific surface area (Surface Area) of the powder is measured by nitrogen adsorption and is calculated by BET (Brunauer, Emmett, Teller). In Table 2, the primary particle size of the tin oxide powder is the smallest in Example 2, and the value of the specific surface area is also the largest in Example 2. Bars of 10 L of gas per minute are supplied while supplying ultrasonic waves. It can be seen that the finest powder was obtained when bubbling at speed.

Table 3 shows the values of the primary particle size, relative sintered density difference and specific surface area by aging time. Among the dXRD values, 1st, 2nd, and 3rd values are calculated from the respective peaks of the X-ray diffraction pattern as described above, and represent particle sizes for different crystal growth directions. Particle size from the first (1st) peak to the [110] direction, particle size from the second (2nd) peak to the [101] direction, and from the third (3rd) peak to the [211] direction of the X-ray diffraction pattern Particle size can be obtained.

When the particle size in the [110] direction is 1 in Example 3, the particle size in the [101] direction is 1.25, and the particle size in the [211] direction is 6. Similarly, when the particle size in the [110] direction is 1 in Example 4, the particle size in the [101] direction is 0.45 and the particle size in the [211] direction is 0.83, and in Example 5 [110] When the particle size in the direction is 1, the particle size in the [101] direction is 1.59, and the particle size in the [211] direction is 1.35.

In Table 3, the tin oxide powder aged for 9 hours showed a wide distribution of dXRD values, so that the crystals did not grow uniformly, compared to 12 hours (Example 4) and 15 hours (Example 5). Since tin oxide powder aged during) was not large in the distribution of dXRD values, it can be seen that the crystals were grown uniformly compared to the case of Example 3.

As such, when the crystal size of the tin oxide powder is analyzed by the X-ray diffraction pattern, the crystal size in the [110], [101], and [211] directions, which are the main growth directions, can be obtained, and the aging time is 12 hours. In the case of 4 it can be seen that the tin oxide powder is most uniformly grown for each crystal direction.

In Table 3, the relative sintered density difference is obtained by measuring the density of the target by making an ITO target with tin oxide powder according to each aging time, and calculating the difference from the theoretical density to calculate the relative density (e.g., Shown as 99.5691% for density). Then, the difference between the density of the target according to Example 4 and Example 5 was calculated based on the density of the target according to Example 3. In other words, the relative sintered density difference is a value obtained by subtracting the relative density of Example 3 from the relative sintered densities of Examples 4 and 5. As a result, the sintered density was the largest in Example 4 aged for 12 hours.

And, when comparing the specific surface area values of Examples 3 to 5, the case of Example 3 and Example 4 is similar, but in Example 4, the sintered density is larger and the primary particle size is also determined. Since it appears uniform along the direction, it can be seen that the finest and most uniform powder is obtained after aging for 12 hours.

Hereinafter, with reference to FIGS. 8 to 10 compare the physical properties of the tin oxide powder prepared according to the present invention.

8 is an electron scanning micrograph of the surface of the sintered body prepared from the tin oxide powder prepared according to Example 3 of the present invention, the magnification of which is 1,000 times, and FIG. 9 shows the tin oxide powder prepared according to Example 4 of the present invention. The magnification is 1,100 times the magnification of the surface of the sintered compact manufactured by the present invention. FIG. 10 is the magnification of the electron scanning micrograph of the surface of the sintered compact made of the tin oxide powder prepared according to Example 5 1,000 times. Comparing each picture, the particle size of FIG. 9 is the smallest and the particle size distribution is uniform.

As described above, according to the present invention, an ultrasonic wave generating apparatus is included in the reaction apparatus for preparing tin oxide, the reaction rate can be increased, and fine tin oxide powder can be obtained. In addition, by adding a device for bubbling gas into the reactor, it is possible to more effectively increase the reaction rate, to produce finer and more uniform tin oxide powder, and to add a measuring device to the reaction device to measure the reaction rate in real time. It can increase the efficiency of the manufacturing process.

In addition, according to the method for preparing tin oxide according to the present invention, the reaction rate can be increased by supplying ultrasonic waves while bubbling gas, and the primary particle size of the tin oxide powder is controlled by adjusting the rate of blowing gas and the intensity of ultrasonic waves. And specific surface area. In addition, by adjusting the maturation time and pH of the metastanic acid produced by the reaction of metal tin and nitric acid, a tin oxide powder having a small primary particle size, a large specific surface area, and an even crystal direction of crystal growth can be obtained. Can be prepared.

As described above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

Claims (20)

Reactor; A support unit for supporting metal tins spaced a predetermined distance from the bottom surface of the reactor; And An ultrasonic wave generating unit for supplying ultrasonic waves into the reactor, Reactor for producing tin oxide for producing a precipitate by reacting the metal tin with an aqueous solution of nitric acid. The method of claim 1, The reaction apparatus for producing tin oxide further comprises an aeration apparatus for generating bubbles by supplying gas. The method of claim 2, The aeration device, A gas supply unit supplying a gas; A gas transfer unit configured to transfer the gas generated from the gas generator into the reactor; And Reaction apparatus for producing tin oxide, characterized in that it comprises a bubble generating unit for generating bubbles by blowing the gas transferred from the gas transfer unit inside the reactor. The method of claim 2, The reaction apparatus for preparing tin oxide further comprises gas chromatography (GC) equipped with a thermal conductivity detector (TCD). The method of claim 1, The ultrasonic generating unit, An oscillator disposed outside the reactor and generating ultrasonic waves; And The reaction apparatus is disposed inside the reactor, and comprises a vibrator for transmitting the ultrasonic wave generated from the oscillator into the reactor. The method of claim 1, The ultrasonic generating unit, An oscillator disposed outside the reactor and generating ultrasonic waves; And Reactor attached to the outer wall of the reactor, comprising a vibrator for transmitting the ultrasonic wave generated from the oscillator into the reactor. The method of claim 1, The ultrasonic generating unit, An oscillator for generating ultrasonic waves and a vibrator for transmitting the ultrasonic waves to the reactor, Reactor apparatus for producing tin oxide, characterized in that the ultrasonic wave is supplied to the reactor through a medium disposed between the reactor and the ultrasonic wave generating unit. The method of claim 1, The intensity of the ultrasonic wave is 0.1 to 3kW, the reaction apparatus for producing tin oxide. The method of claim 3, The gas is at least one gas selected from the group consisting of inert gas, nitrogen gas and compressed air reaction apparatus for producing tin oxide. In the manufacturing method of the tin oxide powder comprising a precipitate forming reaction step of forming a precipitate by introducing metal tin, water and nitric acid into the reactor, The precipitation forming reaction step is a tin oxide powder manufacturing method comprising the step of blowing the gas while blowing the inside of the reactor while supplying ultrasonic waves in the reactor. The method of claim 10, The precipitation forming reaction step, Injecting metal tin and water into the reactor; Blowing gas into the reactor; Supplying ultrasonic waves into the reactor; And Adding nitric acid to the reactor. The method of claim 11, The ultrasonic wave is supplied to the inside of the reactor from before the addition of the nitric acid until the end of the precipitation formation reaction. The method of claim 10, Wherein the gas is supplied into the reactor at a rate of 1 to 5 times the reactor capacity per minute. The method of claim 10, At least one gas selected from the group consisting of inert gas, nitrogen gas and compressed air is blown into the reactor. The method of claim 10, And maintaining the entire surface of the metal tin to be exposed to the nitric acid during the precipitation forming reaction. The method of claim 15, And the bubbling occurs on the surface of the metal tin. The method of claim 10, The intensity of the ultrasonic wave is a method for producing tin oxide powder, characterized in that 0.1 to 3kW. The method of claim 10, Method for producing a tin oxide powder characterized in that the precipitate formed from the precipitation forming reaction step is aged for 11 to 13 hours. The method of claim 10, Method for producing a tin oxide powder, characterized in that for neutralizing the precipitate formed from the precipitation forming reaction step to pH 4 to 8. A tin oxide prepared by the method of claim 10, wherein the crystal size in the [101] direction is 0.4 to 1.6 times the crystal size in the [110] direction, and the crystal size in the [211] direction is 0.6 to 1.4 times. powder.

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